Donald Trump urged Russian agents to "find" his Democratic rival Hillary Clinton's emails and release them, an unprecedented move by a candidate for president encouraging such a foreign breach.

"Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing," the GOP presidential nominee said at a news conference in Miami on Wednesday. "I think you will probably be rewarded mightily by our press."

Trump was referring to the ongoing controversy surrounding the private server Clinton used while secretary of state.

Separately, the Democratic National Convention in Philadelphia this week was upended by a release of hacked emails from the party committee believed to have been orchestrated by Russia. While the motive for intrusion and release of emails isn't known, many Democrats have speculated that it's a possible attempt to influence the outcome of this year's presidential election.

Pressed by NBC's Katy Tur as to whether he had any "pause about asking a foreign government ... to interfere, to hack into the system of anybody's in this country," Trump dismissed that idea and told Tur to "be quiet."

Clinton's campaign responded in disbelief and outrage to Trump's comments.

"This has to be the first time that a major presidential candidate has actively encouraged a foreign power to conduct espionage against his political opponent. That's not hyperbole, those are just the facts," Clinton senior policy adviser Jake Sullivan said in a statement. "This has gone from being a matter of curiosity, and a matter of politics, to being a national security issue."

The Trump campaign appeared to try to clean up Trump's comments with a statement from his running mate, Mike Pence.

"The FBI will get to the bottom of who is behind the hacking" of the DNC emails, said Pence. If it was Russia, "I can assure you both parties and the United States government will ensure there are serious consequences."

The Indiana governor called it "outrageous" that Democrats were "singularly focusing on who might be behind" the breach and not the fallout from the leaked emails, which resulted in the ouster of Democratic National Committee Chairwoman Debbie Wasserman Schultz after some revealed the DNC was rooting for Clinton as their nominee and worked to handicap Bernie Sanders.

'I'm not going to tell Putin what to do'

But then Trump, taking to his usual medium of Twitter, doubled down on his comments earlier just minutes later.

Later Wednesday, Trump senior communications adviser Jason Miller maintained that the presidential candidate was simply saying anyone with Clinton's emails should turn them over to federal authorities.

Throughout the campaign, Trump has praised Russian President Vladimir Putin, whose rule has become increasingly authoritarian. In the press conference at his own golf course, the GOP presidential nominee again said he hoped he could work with Putin and threw cold water on the idea that the Russians were behind the DNC hack.

"I'm not going to tell Putin what to do. Why should I tell Putin what to do?" Trump retorted. "He already did something today where he said don't blame them, essentially, for your incompetence."

Former CIA Director Leon Panetta called Trump's comments "totally outrageous" and questioned his loyalty to the United States.

"I just think that that's beyond the pale," Panetta, who is backing Clinton, said. "I think that kind of statement only reflects the fact that he truly is not qualified to be president of the United States."

'Zero' Ties to Russia

Trump repeatedly batted away questions about whether he might have ties to Russia, saying "Zero! I will tell you right now, zero. I have nothing to do with Russia, yes?"

On Putin – who has called Trump "bright" and whom Trump has praised as a strong leader – Trump said they've never spoken. Trump said he wants to have "friendly" relations with Russia if he's elected but denied any connection to the Russian government or investors.

"I don't know who Putin is. He said one nice thing about me. He said I'm a genius. I said thank you very much to the newspaper and that was the end of it. I never met Putin," Trump said.

Hack Trump's Taxes?

Former Obama advisor David Axelrod also weighed in on Trump's comments, suggesting on Twitter that Russian hackers should go searching for Trump's tax returns - which he has yet to release, breaking a long tradition among leading presidential candidates.

Trump reiterated that he has no plans to release his tax returns until an audit is completed - which may not be finished until after the November elections.

"It depends on the audit – not a big deal," Trump said. He noted that he's already put out some financial documents, though not the tax forms that are typically released by major presidential candidates, often during the primary season. Trump suggested that's unnecessary: "I built an unbelievable company, tremendous cash, tremendous company with some of the great assets of the world," he said.

As NPR has reported before, there's no legal obstacle to releasing tax returns while an audit is ongoing.

Related Content

The Democratic National Convention made history Tuesday evening: Amid applause, shouts, cheers and in some cases tears, the delegates on the floor of the Wells Fargo Center in Philadelphia nominated Hillary Clinton for president of the United States.

Clinton is now the first female presidential candidate of a major American party.

Delegates will vote for their nominee and Bill Clinton will speak on Day 2 of the Democratic National Convention in Philadelphia. You can watch the convention livestream here all day, and the NPR/PBS NewsHour coverage starting at 7 p.m. Central Time.

The first day of the Democratic National Convention in Philadelphia kicks off with speeches by First Lady Michelle Obama, Sen. Elizabeth Warren and the party's presidential runner-up, Sen. Bernie Sanders. You can watch the convention livestream here all day, and the NPR/PBS NewsHour coverage starting at 7 p.m. Central Time.

After a tumultuous Republican National Convention, Texas Democrats are heading to Philadelphia anticipating relative unity — relative being the key word — as they formally nominate Hillary Clinton for president.